This invention relates to the separation of concentrically disposed pipes which have been cemented together. More particularly, this invention relates to the non-destructive separation of such pipes.
In the oil industry, when an oil well is found to be "dry" or after depleting the oil reserves from the well, the drill strings along with their outer casings are extracted from the oil well, and in the standard practice of the industry, an attempt is made to salvage the innermost drill string. Using a known technology, the innermost drill string is salvaged by longitudinally cutting in two places over the entire length of the outer casing and any intermediate drill strings. The longitudinal cutting of the outer casing and intermediate drill strings is accomplished by oxygen-acetylene burning or high pressure water-blasting. In the known technology, as just described, the outer casing and intermediate drill strings are completely severed, thereby being able to salvage the innermost drill string by chipping away the cement portion attached thereto. The chipping away of the cement portion from the innermost drill string is often done manually which is a cumbersome and time-consuming process. Since the completely cut outer casing and any intermediate drill strings cannot be reused, they are often scrapped or melted. As often done, the outer casing and intermediate drill strings are scrapped which consequently litter the surrounding areas where the oil drilling is done.
This invention generally is concerned with a system for salvaging cemented concentric piping members. More particularly, by the use of this invention it is possible to separate the concentric piping members from the concrete portions in order to salvage all the piping portions thereof. This is accomplished by use of a ramming machine already known in the prior art for the purpose of installing pipes in the ground without the need for excavation.
The publication of Vibra King Inc. entitled "ACCU-RAM.RTM. Powerful Ramming Machines" in its entirety teaches the air hammer device which may be employed in shattering or ramming the concrete portions of the cemented concentric piping members in this invention.
The ACCU-RAM.RTM. ramming machine sold by Vibra King, Inc., as described in the aforementioned publication, is made for trenchless pipe-laying. Piping with nominal diameters up to 55 inches are inserted into the ground, without excavating, by the ramming machine which is powered by compressed air. The key to the use of the machine is impact. FIG. 3 shows the operation of the ramming machine for inserting a pipe in the ground. The pipes are actively driven forward under impact by the ramming machine which can be adapted to drive various pipe sizes using the taper locking ram cone or shoe which is illustrated in the publication and in FIG. 7.
Depending on pipe diameter, distance to be covered, soil conditions, and type of machine employed; propulsion speeds up to 30 feet per hour can be achieved. Air consumption is between 141 and 1272 cfm. The thrust power is the key factor in this kind of propulsion technology. The ramming machines develop thrusts of 80 to 1500 tons. Exact alignment can produce pushes dead on target.